Spinneret plate



W my. 7/ /4,//// A a -A. D. SIEGEL SPINNERET PLATE Filed April 16, 1962March 23, 1965 ATTORNEY 2 h w 2 a 4 I 6 W W ML r r 7 W 4 M J ig i 4/ 2;;k m R A United States Patent 3,174,183 SPEQNERET PLATE Arthur D. Siege],Cedar Grove, Ni, assignor to United States Rubber Company, New York,N.Y., a corporation of New Jersey Filed Apr. 16, 1962, Ser. No. 187,607Claims. (61. 18-8) This invention relates to a spinneret plate formeltspinning of fine filament synthetic yarn. More particularly, itrelates to a spinneret plate provided with very small diameter spinningholes of high capillary ratio.

The practice of making spinning holes in spinneret plates by drilling iswell-known in the art. Similarly, the practice of employing pre-drilledinserts inserted in relatively large holes in a spinneret plate is alsoquite common. Even when very small diameter spinning holes are desiredin such plates or inserts, it is feasible to drill such holes whenlength to diameter ratio is not too high, say, in the magnitude of 4/1or less. However, the melt-spinning of high quality fine filament yarnsfrom certain synthetics, including polypropylene, is believed to requireor be materially aided by the employment of a spinneret plate havingsmall diameter spinning holes of relatively high capillary ratios, thatis, length to diameter ratios in excess of /1. Length to diameter ratiosof up to 50/1 are believed to have a beneficial effect on such spinning,yarn tenacity and spinning stability being improved and melt fracture orirregular extrusion at high spinning rates being suppressed.

Ordinary drilling methods are not satisfactory for providing such fine,high capillary ratio spinning holes, because drills of the requireddiameter usually break long before they have reached the desired depth.

It is, accordingly, an object of this invention to provide a novelspinneret plate for melt-spinning of fine synthetic yarns having aplurality of small diameter, high capillary ratio spinning holes.

A still further object is to provide a novel seal between insertmounting holes in 1a spinneret plate and relatively thin walled insertsprovided with high capillary spinning holes which are mounted in suchmounting holes.

For a better understanding of the present invention together with otherand further objects thereof, reference is had to the followingdescription, taken in conjunction with the accompanying drawings, andits scope will be pointed out in the appended claims.

In the drawings:

FIG. 1 is a sectional view of a portion of a spinneret plate showing thestructure of one spinning hole in said plate;

FIG. 1a is a larger scale, partially sectioned detail of FIG. 1 showingparticularly the seal between the spinning hole insert and the mountinghole in the spinneret plate:

FIG. 2 is a partially sectioned view of a completely equivalentalternative form of the invention; and

FIGS. 3 through 8 illustrate six steps in the method of making thespinneret plate section illustrated in FIG. 1.

Referring now to the drawings, wherein like reference numerals denotecorresponding parts throughout the several views, FIGS. 1 and 1aillustrate the construction of the spinneret plate of this invention inthe region of one of the several spinning holes, this identicalconstruction being repeated for each spinning hole in the spinneretplate. At each spinneret hole location, a mounting hole 1 is provided inthe plate 2 extending completely therethrough from one face 3 of theplate 2 to the opposite fax 4. The hole 1 is comprised of a first bore 5extending from one face 3 to a depth intermediate between the two faces3 and 4 and usually through somewhat more than one-half the thickness ofthe plate 2, and a smaller diameter second bore 6, coaxial with thefirst bore and 3,174,183 Patented Mar. 23, 1965 we C communicatingbetween the bottom of said first bore and the opposite face 4. Thejunction or transition zone between the two coaxial bores 5 and 6 ischaracterized by a relatively sharp shoulder 7 at the plane ofintersection of the smaller diameter bore 6 with the bottom of thelarger diameter bore 5.

Mounted in hole 1 so that its end faces 11 and 12 are substantiallyflush with faces 3 and 4 of the plate 2 is a slender insert 10. Insert11) is comprised of a relatively large diameter zone 13 having anoutside diameter slightly smaller than the inside diameter of the largerbore 5, a smaller diameter zone 14 having an outside diameter slightlysmaller than the inside diameter of the smaller bore 6 and a taperedzone 15 providing a relatively gradual transition between the largerdiameter zone 13 and the smaller diameter zone 14. Passing completelythrough insert 10 from the large end face 11 to the small end face 12and substantially coaxial with insert 10 is a high capillary ratiospinning hole 16.

As noted previously with reference to the outside diameters of theseveral zones of the insert 10, there are slight clearances betweenlarger diameter zone 13 and the bore 5 and between smaller diameter zone14 and the smaller bore 6. However, tapered zone 15 is in tightinterference fit relationship with shoulder 7, thereby providing aliquid-tight seal between plate 2 and insert 10 at the plane of shoulder7. While, ideally, the sharp shoulder 7 might be chanacterized by aright angle step, it has been found that a shoulder angle on such asthat formed by the intersection of the smaller diameter bore 6 with theconical impression 8 left by a drill point used for forming larger bore5 will provide an adequate seal. This is approximately a 60 angle.However, because of the clearances between the insert 1% and the hole 1,a shoulder angle on which is approximately equal to the taper angle ,6would admit the possibility of fluid leakage between the plate 2 and theinsert 10.

While it is to be clearly understood that the spinneret plate which isthe subject of this invention is normally provided with a multiplicityof spinning holes arranged in a suitable pattern, the method of makingsuch a plate will be described herein in terms of making a singlespinning hole, all of the spinning holes of the plate being of similarconstruction. In describing this method, reference is had particularlyto FIGS. 3 through 8 taken in numerical order.

As shown in FIG. 3, spinneret plate 2 is first drilled with a bore 5extending from one face 3 of the plate 2 to a depth intermediate betweenthe faces 3 and 4 and usually slightly more than one-half the distancebetween said two faces, the drill point leaving a conical impression 8at the bottom of the bore 5.

Next, as shown in FIGS. 4 and 5, a smaller diameter bore 6 is drilledfrom the bottom of the bore 5 to the opposite face 4 of the plate 2.While it has been found helpful in achieving substantial coaxiality ofbores 5 and 6 to start the drill for the smaller diameter bore 6 in theconical impression 8 at the bottom of the first bore 5, with adequatedrilling jigs provided with hard collars, the same result could probablybe achieved by drilling the two bores 5 and 6 from opposite faces of theplate 2.

Next, referring to FIG. 6, slender drawn tubing, such as that known ashypodermic tubing, having an outside diameter slightly smaller than theinside diameter of the larger bore 5, is cut to a length somewhat longerthan the thickness of the plate 2. This tubing, being drawn, is providedwith a central hole 16 having a much higher capillary ratio than couldbe achieved by drilling and having an outstandingly regular circularcross-section. Alternatively, tubing having a non-circular central holemay be used for spinning fibers of non-circular cross-section. As shownin FIG. 7, this tubing insert is then surface ground at one end toproduce a zone 14 having an outside diameter slightly smaller than theinside diameter of the smaller bore 6 and a transition Zone between thesmaller diameter zone 14 and the original diameter zone 13 having arelatively gradual taper. The length of smaller diameter zone 14 shouldslightly exceed the depth of the smaller bore 6 in the plate 2.

Finally, as shown in FIG. 8, the finished insert 10 is driven, smallerdiameter end first, into mounting hole 1 in plate 2 until the taperedzone 15 of the insert 10 is in liquid-tight interference fitrelationship with the shoulder 7 formed by the intersection of smallerbore 6 with the conical drill point impression 8. While it has beenfound that a satisfactory seal can be obtained by simply tapping theinsert 10 into place with a hammer, equally good results could probablybe achieved by pressing the insert 10 into place. It is believed thatthe sealing effect is at least enhanced by the employment of relativelythin walled inserts. Tubings having inside diameters of from .010" to.035" and wall thicknesses of from .005 to .010" have been found to sealtightly against the shoulder in the mounting hole when employed asinserts.

When the insert 10 has been pressed into sealed relationship with thehole 1, the end faces 11' and 12 of the insert extend beyond the faces 3and 4 of the spinneret plate 2. The plate 2 is, consequently, finishedto the structure shown in FIG. 1 by grinding the end faces 11 and 12 ofthe insert 10 flush with the faces 3 and 4 of the spinneret plate 2.

A 1" thick spinneret plate having spinning holes of .023 diameter and a/1 capillary ratio has been made by the method described herein and hasper formed with good results, the spinning hole being arranged in threeconcentric circles of 1", 2" and 3" diameters containing, respectively,5, 12 and 18 spinning holes. The inserts were made from .023" I.D.,.036" O.D. stainless steel drawn hypodermic tubing cut to one andone-quarter inch length. For a distance of one-half inch from one endthereof, each insert was ground to .033" O.D., the transition zone fromthe .033" O.D. zone to the .036" OD. zone being a substantially uniformtaper approximately long. Each mounting hole in the spinneret plate wasdrilled from the inside face to a depth with a .036" drill and wasdrilled through to the opposite face with a .033 drill. The drills tendto cut slightly oversize holes thereby providing the aforementionedslight clearances -for the inserts. The inserts were sealed in themounting holes by tapping with a hammer. Clearance between inserts andholes has been found not to be critical and selective fitting is notnecessary.

The structure shown in 'FIG. 2 is identical to that shown in FIG. 1except that the insert 10 is assembled into a mounting hole 1a in ataper pin 9 which, in turn, is subsequently assembled into a taperedhole 17 in spinneret plate 2 and is then ground flush, becoming, for allpractical operational purposes a part of the spinneret plate 2, itself.Taper pins 1 long by .250" diameter at the large end with a taper of A"per foot have been used successfully. The chief advantage'of using taperpins as opposed to mounting the spinning hole inserts ltl directly inthe holes 1 drilled in the plate}, as shown in FIG. 1, is thatindividual taper plugs can be replaced or removed for maintenancewithout destroying the entire plate. It is to be noted, however, thatthestructure and method described and claimed herein are intended to applyto spinning hole assemblies of the type described whether made directlyin mounting holes in the spinneret plate or in taper plugs or otherinserts which are intended to be subsequently inserted in larger holesin 1a spinneret plate and to function therein essentially is a part ofsaid plate.

While a preferred form of the invention has been shown and describedherein, it will be appreciated that this is for the purpose ofillustration and that modifications and changes may be made thereinwithout departing from the spirit and scope of the invention.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A spinneret plate assembly having at least one high capillary ratiospinning hole comprising:

(a) a plate provided with at least one mounting hole passingtherethrough and having at least two zones of different diameters, thejunction between at least two of saidzones of different diameters beingcharacterized by a relatively sharp shoulder; and

(b) a tubular insert in each said mounting hole, said insert having ahigh capillary ratio spinning hole passing therethrough and an externalsurface of revolution including a tapered portion in liquid-tightcontact with said shoulder of said mounting hole.

2. A spinneret plate assembly having at least one high capillary ratiospinning hole comprising:

(a) a plate provided with at least one mounting hole passingtherethrough, said mounting hole including at least two bores ofdifferent diameters, the junction between at least two of said bores ofdifferent diameters being characterized by a relatively sharp shoulder;and

(b) a tubular insert in said mounting hole, said ininsert having a highcapillary ratio spinning hole passing therethrough and an externalsurface of revolution including a relatively gradually tapered portionin liquid-tight driven contact with said shoulder of said mounting hole.

3. A spinneret plate assembly including:

(a) a plate having at least one hole extending therethrough from face toface, each such hole comprising a first bore opening on one face of saidplate and a second bore of slightly smaller diameter than said firstbore communicating between said first bore and the opposite face of saidplate, said first and second bores being substantially coaxial, thejunction between said second bore and said first bore defining arelatively sharp shoulder; and

(b) a tubular element having a high capillary ratio passage therethroughinserted in each said hole, the exterior surface of each said tubularelement having a tapered section, said tapered section being in drivencontact withsaid sharp shoulder of said hole, whereby an effectiveliquid-tight seal exists between said tapered section and said shoulder.

4. A spinneret plate assembly having at least one high capillary ratiospinning hole comprising:

(a) a plate provided with at least one mounting hole extending throughthe entire thickness of said plate from face to face thereof and havinga zone of relatively small diameter adjacent to one face of said plateand at least one zone of larger diameter adjacent to said small diameterzone, the junction between said small diameter zone and said adjacentzone being characterized by a relatively sharp shoulder; and

(b) a number of tubular inserts corresponding to the number of saidmounting holes, formed from drawn tubing, each at least as long as thethickness of said plate, each said insert having a uniform inside diameter equal to the desired diameter of each spinning hole and an externalsurface of revolution, a length of said external surface of revolutionadjacent one end of each said insert having a diameter slightly smallerthan the diameter of said small diameter zone of its correspondingmounting hole and another length thereof, separated from said firstmentioned length by a relatively gradually tapered length, having adiameter slightly smaller than the diameter of said larger diameter zoneof its corresponding mounting hole adjacent to said small diameter zoneof said mounting hole;

(0) each said insert being mounted, small diameter end first, in itscorresponding mounting hole, from the side opposite said small diameterzone thereof, so that said tapered length of each said insert is inliquid-tight interference contact with said sharp shoulder of itscorresponding mounting hole.

5. A spinneret plate assembly provided with at least one small diameterhigh capillary ratio spinning hole, each said spinning hole comprising:

(a) A first cylindrical hole in said plate extending from one facethereof to a plane intermediate between the two faces thereof, saidfirst hole having a flat to relatively flat conical bottom;

(b) a second cylindrical hole in said plate of smaller diameter thansaid first hole, said second hole being substantially coaxial with saidfirst hole and extending between the bottom of said first hole and theopposite face of said plate;

(0) said first and second holes together comprising a stepped mountinghole of two diameters the transition between which is characterized by arelatively sharp shoulder; and

(d) a tubular insert having a uniform inside diameter spinning hole andcomprising a first tubular zone having an outside diameter less than theinside diam- 5 eter of said first hole and greater than the insidediameter of said second hole, a second tubular zone, substantiallycoaxial with said first tubular zone, having an outside diameter lessthan the inside diameter of said second hole, and a transition zonebetween said first and second tubular zones in the form of a relativelygradual taper;

(e) said insert being inserted in said mounting hole so that saidtransition zone of said insert is in liquidtight interference contactwith the intersection of said second hole and said bottom of said firsthole.

References Cited by the Examiner UNITED STATES PATENTS 2,341,555 2/44Jones 18-8 2,618,989 11/52 Cupler 76107 2,879,676 3/59 Burkhardt et al.76-107 3,006,026 10/61 Martin et al. 188 3,038,420 6/62 Smmohr 18-8 XFOREIGN PATENTS 1,102,340 3/61 Germany.

30,306 1910 Great Britain.

WILLIAM J. STEPHENSON, Primary Examiner.

ROBERT F. WHITE, Examiner.

1. A SPINNERET PLATE ASSEMBLY HAVING AT LEAST ON HIGH CAPILLARY RATIOSPINNING HOLE COMPRISING: (A) A PLATE PROVIDED WITH AT LEAST ONEMOUNTING HOLE PASSING THERETHROUGH AND HAVING AT LEAST TWO ZONES OFDIFFERENT DIAMETERS, THE JUNCTION BETWEEN AT LEAST TWO FO SAID ZONES OFDIFFERENT DIAMETERS BEING CHARACTERIZED BY A RELATIVELY SHARP SHOULDER;AND (B) A TUBULAR INSERT IN EACH SAID MOUNTING HOLE, SAID INSERT HAVINGA HIGH CAPILLARY RATIO SPINNING HOLE PASSING THERETHROUGH AND ANEXTERNAL SURFACE OF REVOLUTION INCLUDING A TAPERED PORTION INLIQUID-TIGHT CONTACT WITH SAID SHOULDER OF SAID MOUNTING HOLE.